Paper-coating material and process of making



mama neaa, iea a ran ass teases "ET @E.

WILLIAM J. LAWRENCE, .OF KALAMAZOO, MICHIGAN.

PAPER-COATING MATERIAL AND PROCESS OF No Drawing.

To allwhom it may concern."

Be it known that I, WILLIAM J. Law

' ing, of which the following is a specification.

This invention relates to improvements in paper coating material and process of making. 1

The objects of the invention are: First, to provide an improved coating material which is highly colloidal and may be applied to the paper in a more concentrated form than is usual with coating material such as satin white, thus increasing the weight of the coating which may be applied at one treatment of the paper and lowering the drying cost of the same.

Second, to provide an improved coating material which does not coagulate the adhesive, such as casein size, used as a binder, and does not cause the tinting or coloring to fade Where it is added to the coating solution.

Third, to provide an improved coating material which may be used with. good 'results in the production of dull finish coated papers as well as with' high luster coated papers and the color of which is not affected by calendering.

Fourth, to provide an improved coating material which results in a smooth, p even surface, which is desirable for printing and lithograph work,

Fifth, to provide an improved coating material which results in paper which is not readily broken or. cracked in folding or bending.

I am awarethat lime has been used or has entered into the manufacture of satin white and similar coating compositions but, so far as I have observed, the result has been a harsh, unstable coating composition. While the baseof my composition the class of satin white now employed.

In the preparation of my improved coating composition I combine carbon dioxide Application fifled December 18, 1922. Serial No. 607,700.

or carbonic acid gas with. lime, preferably by passing carbon gas through a solution of milkof lime, after which the product may be concentrated, filtered, and pressed or dried for handling and shipment or storage.

To the carbonated lime or calcium carbonate thus produced I preferably add aluminum hydroxide or its equivalent in the proportion of 40% of the alumina to of the lime, the object of the alumina being to .add luster when the coating is applied to a paper and calendered. The proportions mentioned contemplates dry weight but may, however, be very. greatly varied with. desirable results. Adhesive such as casein size or glue or such other materials as are usedin sizing may be added.

My improved coating material does not coagulate the size used as a hinder or adhesive. It is an entirely neutral product and does not cause the tinting colors to change or fade where the tinting colors are added to the coating solution.

My improved coating material is adapted for dull finish and also for high luster coated papers and, on account of the finely di- A still further advantage is that the f paper treated or coated with my improved coating material has superior, folding ualities, that is, it is not likely to crac or break on folding and because of the very smooth, even surface obtained the paper is very desirable for fine. printing and lithograph work.

Having thus described my invention, what "I claim as new and desire to secure by Letters Patent, is: I

1. The method of preparing a paper coating composition consisting of carbonating lime by passing carbon dioxide through milk of lime and'mixing the calcium carbonate thus produced withg aluminum hydroxide in the proportions of 60% of the calcium carbonate and 40% of the aluminum hydroxide, dry. weight, and adding casein size.

2. The method of preparing a paper coat ing composition consisting of carbonating ing of carbon dioxide through milk of lime by passing carbon dioxide through milk lime, and aluminum hydroxide.

of lime and mixing the calcium carbonate 6. A paper coating composition compristhus produced with aluminum hydroxide in ing approximately 00% of calcium carbonthe proportions of 60% of the calcium carate, 40% or aluminum hydroxide, and an bonate and 40% of the aluminum hydroxide, adhesive, 1 dry Weight. a '7. A paper coating composition compris- 3. The method of preparing a paper coating approximately 60% oil calcium carboning composition consisting of carbonating ate, and, 40% of aluminum hydroxide. l0 lime by passing carbon dioxide through milk a 8. A paper coating composition comprisof lime and mixing the calcium carbonate ing calcium carbonate, aluminum hydroxide, thus produced with aluminum hydroxide, and an adhesive. and adding casein size, 9. A paper coating composition comprisa. A paper coating composition comprising calcium carbonate and aluminum hying calcium carbonate formed by the passdroxide, 1 ing of carbon dioxide through milk of lime, lln witness whereof, l have hereunto set aluminum hydroxide, and an adhesive. my hand and seal,

5. A paper coating composltion comprising calcium carbonate formed by the passlNlLLllAM J. LAWRENCE. [1a. a] 

